Sometimes my sim not working I can’t call anyone and also opposite person , showing is call failed,how to fix this problem

Thanks for posting in the Apple Support Communities badhan44,

We understand you're having an issue with cellular service, and linked to the support communities from the "If you see No Service or Searching on your iPhone or iPad" article. Were you able to go through and complete the steps outlined on that page?

If so, try the steps in this article as well: If you can't make or receive calls on your iPhone

Take care!